One type of railroad freight car in use today is a hopper car wherein an elongated walled enclosure including one or more hoppers holds material or commodity therewithin. The walled enclosure is mounted on a mobile frame or undercarriage and defines a longitudinal axis for the railcar. When a top of such railcars is closed, as with covers and the like, the railcars can be used to transport corn and other granular materials. In those instances wherein the hopper has an open-top, such railcars are typically used to transport, aggregate, iron ore, coal and other granular commodities. With either design, railroad hopper cars offer an economical method of transporting large quantities of material between distant locations.
To facilitate the discharge of material from the walled enclosure, each hopper is typically configured with two or more longitudinally spaced chutes. Each chute is defined by a series of downwardly slanted walls which terminate toward a bottom of the walled enclosure. That is, and toward a lower end thereof, each chute defines an opening through which the material in the chute is gravitationally discharged upon arrival of the railcar at its intended destination. A gate assembly is arranged in operable association with each hopper opening. Typically, each gate assembly has a rigid frame defining a discharge outlet arranged in general registry with the opening at the bottom of each chute. Each gate assembly further includes a slide door or gate for controlling the discharge of material from the respective hopper. Typically, the door or gate of the gate assembly longitudinally slides on the frame anywhere between and to a closed position, wherein the slide door blocks or extends across the discharge outlet, and an open position, wherein the slide door is positioned relative to the discharge outlet so as to allow or permit material to gravitationally pass from the respective hopper.
With the gate assemblies typically arranged in longitudinally aligned relation relative to each other, the slide door on each gate sometimes inadvertently opens to some degree from its closed position. That is, as the cars are assembled into a train consist, they are purposefully bumped into each other. Moreover, during acceleration and abrupt stops of the train, longitudinal forces are placed on the slide doors which tend to urge them from the closed position toward the open position. Because the slide door movements may be slight, they often go unnoticed whereby allowing commodity to inadvertently escape from the hopper.
Accordingly, most gate assemblies are equipped with some form of lock assembly. The lock assembly inhibits the slide door of the gate assembly from inadvertently moving from the closed position. Various types of mechanisms are provided on the gate assembly and/or car for releasing the lock from a locked condition. Of course, providing a lock assembly in combination with the gate assembly to inhibit inadvertent movement of the slide door from the closed position along with a lock release mechanism adds to both the complexity and overall cost of the gate assembly.
To increase the carrying capacity of each hopper railcar, both the length and width of the walled enclosure have been optimized to the limits permitted by the Association of American Railroads (AAR). To provide sufficient distance for the sliding gates on adjacent assemblies to clear each other as they move toward their open positions, the openings at the bottom of the hopper are typically spaced longitudinally relative to each other. As mentioned, and between adjacent openings, there are angularly inclined or sloped sheets to enhance the gravitational flow of material in each hopper toward the opening. These Applicants recognized and appreciated, the relatively large areas beneath the sloped walls or surfaces of each hopper, however, constitutes wasted space. These Applicants furthermore recognized reducing the spacing between adjacent hopper openings could result in a reduction in the wasted space beneath the sloped walls or surfaces of each hopper. As such, the overall carrying capacity of each railroad hopper car can be advantageously increased without exceeding AAR specifications and the center of gravity of a loaded railcar can be advantageously lowered to enhance stability performance of the car.
Thus, there is a need and continuing desire for a railroad hopper car which allows for rapid discharge of materials from the walled enclosure while optimizing the material carrying capacity of the railcar and enhancing stability performance.